[Bug c++/86299] New: no member named 'value'

[zhonghao at pku dot org.cn]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86299

            Bug ID: 86299
           Summary: no member named 'value'
           Product: gcc
           Version: 8.0.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: zhonghao at pku dot org.cn
  Target Milestone: ---

The code is as follow:

template< typename > struct has_xxx0
{
  template< typename > struct has_xxx0_introspect
  {
    template< typename > struct has_xxx0_substitute ;
    template< typename V > 
    int int00( has_xxx0_substitute < typename V::template xxx< > > = 0 );
  };
  static const int value = has_xxx0_introspect<int>::value;
  typedef int type;
};

has_xxx0<int>::type t;

The code seems to be invalid, but g++ accept the code. In fact, a previous
version of clang++ also accepts it, but was fixed in
https://bugs.llvm.org/show_bug.cgi?id=7385

The latest clang++ produces the following error message:
error: no member named 'value' in 'has_xxx0<int>::has_xxx0_introspect<int>'
      static const int value = has_xxx0_introspect<int>::value;
                               ~~~~~~~~~~~~~~~~~~~~~~~~~~^